Ok, I found this today, north Hertfordshire on some rough ground/wildflower area. Lots of meadow brown and small torts, a few whites and I think I saw a couple of ringlets but everything was way too quick today.
In flight it looked completely black on the upper surfaces. Because both hindwings were deformed I didn't get any clue from flight pattern because it was flying rather erratically. I'm fairly sure it's a butterfly,.not a moth due to the clubbed antennae.
The only thing I can come up with is a fully melanistic ab. Of Ringlet? But that is just a stab in the dark.
The second picture isn't a true representation of the colours of it, due to the sun. The grey of the first is spot on though
